Greenpeace activists create ‘boulder barrier’ in North Sea to deter industrial fishing

The boulders were loaded onto the Greenpeace ship Arctic Sunrise in Le Havre and dropped to form a barrier around the Southern North Sea marine protected area – the UK's most bottom-trawled MPA. This area is particularly important for harbour porpoises, supporting nearly 20% of the UK North Sea population.

Despite its MPA status, there are no restrictions on fishing in most of the Southern North Sea. Bottom trawlers, dredgers and other industrial fishing vessels scour it daily, logging more than 37,200 fishing hours in the protected zone in 2025 alone.

Destructive fishing practices

Bottom trawlers and dredgers tore through a cumulative 55,600 sq km of MPA seabeds in 2025, an area 58 times the size of Dartmoor national park, according to a Greenpeace analysis. Greenpeace UK described this activity as akin to 'a bulldozer tearing through a treasured national park'.

Ocean park declaration

The 'boulder barrier' has effectively closed 116 sq km (about 45 sq miles) of the Southern North Sea MPA to bottom trawling. Over the coming days, the Arctic Sunrise will patrol the area to deter other kinds of industrial fishing. The activists have declared the zone an 'ocean park', in the spirit of Britain's national parks.

The Southern North Sea MPA lies along the east coast of England, from north of Dogger Bank to the strait of Dover in the south. It is intended to protect porpoise populations by ensuring the 'availability of prey is maintained' – an objective Greenpeace says is contradicted by intensive fishing in the area.

Political support

Labour MP Kerry McCarthy, a former climate minister and member of the all-party parliamentary group for the ocean, added her name to one of the boulders tipped into the North Sea. She emphasized that industrialized fishing is having a 'hugely destructive impact on our marine environment', with less than 1% of UK seas protected from it.